Systems for acquisition and/or recording data by telemetry have been known and used for many years. Such systems employ an electronic device to sense and measure preselected conditions and to then transmit the information thus obtained to a remote receiver or receivers where the information is recorded and further processed. While there are data acquisition cases where such telemetry systems may be used, there are many other cases where telemetry systems do not operate satisfactorily. This is particularly true in the case of accumulating a mix of biological and/or clinical data from free roaming subjects over relatively long periods of time, for example weeks, months or even years. Typical examples of critical applications are chronobiological data; pre-stress, stress and post-stress data in sequence; long-term isolation data; drug studies; and specific categories of clinical data for chronic periods.
Telemetry does not provide a satisfactory solution for any of the above cases. A free-roaming subject presents significant technical problems for telemetry, particularly in urban environments and in those cases in which the subject moves through substantially different environments in normal movement. The transmission of data through such changing environments may adversely affect the data being transmitted. Moreover, the transmittor frequently requires significant power input which in turn adds significantly to the weight of the system.
Although portable systems have also been developed, a significant problem is that power consumption in the conventional systems is not effectively optimized. The lack of adequate power control in conventional systems greatly restricts the period of time that the system can be used without requiring a replacement battery.
In accordance with the present invention, a data acquisition and recording system is provided which is particularly useful in acquiring and recording biological and/or clinical data over long periods of time from free-roaming, ambulatory subjects. More particularly, the present invention provides a self-contained system for acquiring and recording data which can be worn unobtrusively by the subject under observation for long periods of time and which is capable of accumulating and storing, in a nonvolatile form, extremely large quantities of several classes of data.
The system, including its power supply, is sufficiently small so as not to interfere with the subject's normal activities and is relatively light in weight. Moreover, power usage is specifically controlled so that the system requires extremely low power for its intended operation, and therefore, can be used for long periods of time. For example, various circuits of the system are powered up and powered down as needed continuously during the monitoring process to provide almost continual power control for the optimization of power usage.
One of the problems faced by the worker in the field of chronobiology relates to the acquisition of smooth-profile data for periods substantially in excess of several weeks. Further, it is sometimes necessary to acquire data which includes a number of different parameters such as heart rate, ectopic heart beat, body temperatures, sweat ion-level concentration and other related parameters.
In the clinical and bio-research situation it has become a matter of considerable importance to establish circadian patterns for human and animal subjects. Circadian patterns are expected to be useful in analyses related to the onset of episodic mental problems, the establishment of optimal times for radiation treatment and/or chemotherapy and the selection of crew members for shared-crew missions.
In stress-related studies, the system in accordance with the present invention makes it possible to follow subjects during a pre-stress period, the stress period and post-stress period. Examples may include subjects participating in spaceflight where they would be observed from well before the flight, during lift-off, orbit, reentry, touchdown and for substantial post-flight periods. Special mission members or crews may be studied during pre-mission, mission and post-mission time periods. The air-traffic controller represents another subject for continuous stress/nonstress data acquisition. Controllers can easily be studied continuously on and away from the job through use of the system in accordance with the present invention. Long-term "isolation" data could also be acquired from nuclear submarine crew members and from subjects located for long periods at remote inclement sites, as in exploration missions, both terrestrial and in space. It would be possible to acquire data from scuba divers including related physical parameters of depth, water temperature, pressure and the like. Certainly for undersea habitat research, smooth profile, long-term data acquisition would be possible and would be of great interest.
Subjects used for drug studies are of interest with regard to the collection of heart rate and body temperature data, both during prestudy and over the course of the study. Using such data and other parameters of interest may be of further use to aid in the establishment of optimum time of administration, within the circadian period, of drugs for enhanced efficacy, for reduction of undesirable side-effects and for reduced dosage levels.
From a clinical viewpoint, the patient subject to a periodic arrhythmia is of major interest. Such patients could be followed for extended time periods and the occurrence of arrhythmias adequately recorded including the previous normal ECG-complex, the R--R spacings in milliseconds, the ectopic complex, time of occurrence and other related types of information.